High idle wont go down.............rb20det

[k4rr]

I have a high idle issue.

Must be at 2k I am guessing...

I can unplug the aac and the idle will go down.

(I already swapped out the aac with one from my other motor and cleaned it.)

With it all plugged up if I dsconnet the tps there is no change.

Idle will only drop when I unplug aac.

I have alsot tried unplugging the aac and adjusting the idle screw. I adjusted it all the way down. However it still high when I plug the aac back up.

I also replaced the valve that is under the intake manifold with one off my old engine. It didnt make a difference. I also tried unplugging while the car was running and it didnt make a difference either.......

Any ideas?

[AxiOn419]

How are you running the recirculating valve? Atmospheric or is it routed back into the intake? If it is atmospheric, did you just remove the hose and thats that or did you reposition the MAF sensor to adjust for the difference?

[k4rr]

I am not venting to the atmosphere. It's routed back to the intake...

[AxiOn419]

I am not venting to the atmosphere. It's routed back to the intake...

I see you added an ellipsis to the end of your sentence which indicates to me that you are thinking, "Why is this guy asking me this?" and here is why:

I had the same exact idle issue. Idled around 2000 rpm. Long story short, the problem was a combination of the IACV being set way to high in order to compensate for the lost air that was being blown atmopherically at the time. If the IACV were set properly, the engine would die when coming off of load, presumably becuase the ECU was expecting a lot more air in the engine than what was being delivered. After hooking up a hose to re-route the air into the intake, properly positioning the TPS and adjusting the IACV properly, problem solved.

Just tried sharing what I knew but it appears I will be of no help as I do not know much of your situation beyond what I have posted. Best of luck!

[ripracer]

when mine was doing this, I had to pull out the IACV(one between the intake runners and upper intake) and take it apart. The little springs that holds the diaphragm in place had slipped off.

[silviasgp06]

maybe since when you can unplug the IAVC and idle drops this doesnt apply but...

i once did something on my KA and it caused it to idle high, turns out something was keeping tension on the throttle cable, keeping the throttle body open... oops
Modified by silviasgp06 at 9:13 AM 10/17/2007

[k4rr]

I am thankful for your help.

Well I can unplug the maf. And it will bounce off limp mode. Which tell me my cars is trying to idle higher than 2500. Maybe around 3500......

So I unplugged the aac vlave and the idle went down some. That is the one that I cleaned. But made no difference.

So then I unplugged the plug that goes to the bottom of the TPS. While the AAC valve was unplugged. And then the idle went down to almost like normal it seems. I dont have a tach working in my car so I cannot be for sure.

So I am starting to think it may be a combo of both. However I already replaced the AAC valve and cleaned it. The one on the back of the intake.

I also replaced the idle valve thing. That I dont remeber what it is called. But it's the one under the plenum. I have a spare engine for parts. However I havent checked it for a unhooked spring yet. But I will in a little while. When the engine is cooled down.

I also tried unplugging the purple plug on the valve under the intake. It made no difference.

[AxiOn419]

Are you just guessing at what your idle speed is by listening to the sound? Depending on your exhaust, idle may be lower than what you think because the engine is pretty loud and mean sounding past 1000 RPM.

[k4rr]

Well, I know it higher than 2500. Because if I unplug the maf to make it go into limp mode. It will bounce off the 2500 rpm limiter.

Are you just guessing at what your idle speed is by listening to the sound? Depending on your exhaust, idle may be lower than what you think because the engine is pretty loud and mean sounding past 1000 RPM.

[AxiOn419]

Ahh yes, I see where you mentioned that in your previous post. Just wasn't paying attention.

You said you unplugged your TPS but have you made sure it is properly set in the first place? I would do that before anything else which I will go ahead and assume you have done but figured I would mention it just in case

[k4rr]

Yeah nissan calls that the AAC for some reason.

Well, I fixed my high idle!!!!!!!!!!!!!!!!!!!!!!!!!!!!

It was the calve that was under the plenum with the purple plug. I took it apart and the spring was busted in it too. So I went to the junkyard and pulled one off another nissan and BAM idle is perfect now.!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Ahh yes, I see where you mentioned that in your previous post. Just wasn't paying attention.

You said you unplugged your TPS but have you made sure it is properly set in the first place? I would do that before anything else which I will go ahead and assume you have done but figured I would mention it just in case

Sure, here you go:

Look behind the intake manifold:

Close up:

[AxiOn419]

Awesome, glad to hear you fixed it. What valve are you talking about exactly? Could you take a picture, I am interested in seeing, also what engine did you get the replacement part from?

[ripracer]

YES, I was right. Have fun

[k4rr]

Awesome, glad to hear you fixed it. What valve are you talking about exactly? Could you take a picture, I am interested in seeing, also what engine did you get the replacement part from?

Its the valve that under the plenum has 2 hoses that go to it. If you are standing at your passenger fender and looking over on top of your engine. It is to the left of the throttle and down a few inches.

Best way to fix.

Get a AAC valve off of a KA24DE.

Take off your skyline AAC.

Remove the 4 phillups head bolts off of the back of the ACC. They are *****!!!

So get the right sized phillups head that fits perfect and turn hard as **** with lots of pressure.

Once you have them out take off the black cover and lay it to the side.

Check to see if the spring is broken. If it is that's your problem!

do not try to just remove the spring from the black plastic piece that turns!!!!!! You will mess it up!!!!!!!!!!!

So how do you do it?

Like this Flip it over you will see a very small nut with some red hard goo on it. Break all the goo off with a flathead screw driver and unscrew the nut.

then flip it back over and you can pull out the piece that turns that is connected to the spring. The spring is attached to the casing on one side. just slide it up.

then take your factory AAC valve from you RB engine and put the piece of the AAC you just took out of the KA in the RB AAC case.

Fixed.